Injectable solution of an LHRH antagonist

ABSTRACT

An aqueous injectable soution of an LHRH antagonist, such as Cetrorelix, in an organic, pharmaceutically acceptable acid, such as gluconic acid.

TECHNICAL FIELD

[0001] The invention relates to aqueous injection solutions of an LHRHantagonist with the use of additives of organic, physiologicallytolerated acids and/or surfactants and their production for preventingthe aggregation of LHRH antagonists in solutions. The injectionsolutions, prepared according to the invention, additionally lead to anincrease in the bioavailability and enable the injection volume, whichhas to be applied, to be reduced.

STATE OF THE ART

[0002] For the controlled stimulation of the ovaries, followed by eggcell removal and techniques of assisted reproduction, aside from LHRHagonists (such as triptorelin, buserelin), especially LHRH antagonists(cetrorelix, ganirelix) have been used for some time, since they avoidthe initial increase in endogenous gonadotropin secretion and leadimmediately to a competitive inhibition of the gonadotropin-releasinghormone (EP 0 788 799 A2; EP 0 299 402 B1). The LHRH antagonist,ganirelix, is presently employed in a formulation, which contains 0.25mg of ganirelix in 0.5 mL of an aqueous, mannitol-containing solution inthe form of a ready-for-use injection (Orgalutran®). The LHRH antagonistcetrorelix (Cetrotide®) is presently offered in two forms, as alyophilisate with 3 mg of cetrorelix, combined with a ready-for-usesyringe, which contains 1 mL of water for reconstitution, and as alyophilisate with 3 mg of cetrorelix, combined with a ready-for-usesyringe, which contains 3 mL of water for reconstitution. However, LHRHantagonists are used not only for the controlled stimulation of theovaries, but also for the treatment of the hormone-dependent types ofcancer, such as prostate cancer. Substances such as abarelix (WO98/25642) or cetrorelix (WO 00/47234) could be used for this purpose sothat LHRH antagonists could be an alternative to the market-dominatingagonists (leuprolide, goserelin) in this therapy. Because of therelative poor solubility of abarelix in water or physiological media, asustained release formulation must be used, in order to achieve aprolonged effect. However, there are also indications that a prolongedeffect may also require good solubility of the LHRH antagonists (G.Jiang, J. Stakewski, R. Galyean, J. Dykert, C. Schteingart, P. Broqua,A. Aebi, M. L. Aubert, G. Semple, P. Robson, K. Akinsanya, R. Haigh, P.Riviere, J. Trojnar, J. L. Junien and J. E. Rivier, J. Med. Chem., 2001,44, 453-467).

PRESENTATION OF THE INVENTION

[0003] It is an object of the invention to prepare an injectionsolution, which has a low injection volume and an increasedconcentration of the LNRH antagonist due to the improved solubility ofthe latter. At the same time, the aggregation of the LHRH antagonist inthe injection solution of greater concentration is prevented.

[0004] Surprisingly it was found that organic, physiologically toleratedacids, particularly carboxylic acids and especially hydroxycarboxylicacids, preferably, however, gluconic acid by itself or in combinationwith surfactants such as Tween, clearly improve the solubility of LHRHantagonists, and, with that, clearly reduce the tendency of thesesubstances to aggregate.

[0005] The invention therefore enables LHRH antagonists to be producedin higher concentrations in aqueous solutions for injection. As LHRHantagonists, cetrorelix, teverelix, D-63 153(ac-D-nal-pCl-D-phe-3-D-pal-ser-N-me-tyr-D-H-cit-iso-leu-arg-D-ala-NH₂),ganirelix, abarelix, antide and azaline B may, for example, bementioned. It turned out that an excess of the respective carboxylicacid must be used and that equimolar amounts are not sufficient.Obviously, this effect cannot be explained alone by an in situ formationof salts with existing basic amino acids groups such as arginine,pyridyl alanine or lysine. Likewise, the surfactant concentration mustnot be too high as otherwise the solutions foam excessively andaggregation is induced once again by the surfactants.

[0006] At the same time, these additions make a higher bioavailabilitypossible since they evidently also retard the spontaneous aggregation inthe body after injection or make a more rapid absorption of thesubstance by the site of action possible. It turned out that the lowerpH of such injection solutions (such as 2.5-3) does not have an effecton the local tolerance of the injection. By increasing theconcentration, it is possible to reduce the volume applied, for example,in the case of the 3 mg form of cetrorelix, from 3 mL to 1 mL. It wasalso shown that a good shelf life can be achieved by these additions(see Example 1). When kept for more than 6 months at 24° C. and 60%R.H., there was, admittedly, an increase in contamination; however, inevery case, the content was still clearly above 90% (usually the lowestvalue of the shelf life specification of pharmaceutical products).Cloudiness, as an indication of aggregation, increased only slightly.Cloudiness values of up to 8 FTU (formazin turbidity unit according tothe European Pharmacopoeia) can readily be tolerated. Preservatives,such as phenol or p-chloro-m-cresol do not interfere and can be usedadditionally to preserve the solutions. The use of conventionalstructure-forming agents, such as mannitol, lactose, glucose andfructose is also possible.

DESCRIPTION OF ONE WAY OF CARRYING OUT THE INVENTION Example 1

[0007] 500 mg cetrorelix 2 g Tween 80 2.4 g delta lactone of gluconicacid 95 g of mannitol

[0008] were mixed with water for injection purposes to form 2 L of ahomogeneous solution. The solution was subsequently filtered tosterilize it and filled into ampoules. The ampoules were analyzedinitially and after 6 months at 2° -8° C. and 25° C. at 60% relativehumidity for purity (HPLC), content (HPLC), pH and aggregation(cloudiness).

[0009] Analytical Results: Analysis after 6 months at Initial Analysisafter 6 25° C. and Analysis months at 2°-8° C. 60% R.H. Purity (%) 0.370.69 2.32 Content (%) 100.0 98.7 95.4 pH 3.12 3.16 3.16 Cloudiness (FTU)1.88 2.62 3.92

Example 2

[0010] approx. 500 mg of D-63153

[0011] approx. 100 mg of Tween 60

[0012] approx. 475 mg of mannitol

[0013] were adjusted with aqueous, saturated gluconic acid delta lactonesolution to a pH of about 2.5. A volume of about 50 mL resulted. It wasstirred until a clear solution resulted.

[0014] Analytical Results:

[0015] Initially, the cloudiness of the solution was 2.4 FTU and, after24 hours, it was 2.1 FTU. The purity profile and the content of thesolution (HPLC) remained unchanged.

[0016] Structure of the LHRH antagonist D 63153:

[0017]as-D-nal-pCl-D-phe-3-D-pal-ser-N-me-tyr-D-H-cit-iso-leu-arg-pro-D-ala-NH₂

Example 3

[0018] approx. 100 mg of teverelix

[0019] approx. 100 mg of Tween 80

[0020] approx. 475 mg of mannitol

[0021] were adjusted with aqueous, saturated gluconic acid solution to apH of about 2.5. A volume of about 10 mL resulted. It was stirred untila clear solution resulted.

[0022] Analytical Results:

[0023] Initially, the cloudiness of the solution was 6.8 FTU and, after24 hours, it was 8.4 FTU. The purity profile and the content of thesolution (HPLC) remained unchanged.

[0024] Structure of the LHRH antagonist teverelix:

[0025]ac-d-nal-pCl-phe-3-D-pal-ser-tyr-D-H-cit-leu-ipr-lys-pro-D-ala-NH₂

We claim:
 1. An aqueous injectable solution of an LHRH antagonist whichcomprises an LHRH antagonist and an organic, pharmaceutically acceptableacid.
 2. The aqueous injectable solution of claim 1, wherein said acidis a carboxilic acid.
 3. The aqueous injectable solution of claim 1,wherein said acid is a hydroxycarboxylic acid.
 4. The aqueous injectablesolution of claim 1, wherein said acid is gluconic acid.
 5. The aqueousinjectable solution of claim 1, further comprising a surfactant.
 6. Theaqueous injectable solution of claim 1, wherein said surfactant isTween.
 7. The aqueous injectable solution of claim 1, wherein said LHRHantaginist contains one or more of Cetrirelix, Teverelix, D-63 153(Ac-D-Nal-pCl-D-Phe-3-D-Pal-Ser-N-Me-Tyr-D-H-Cit--Iso-Leu-Arg-Pro-D-Ala-NH₂),Ganirelix, Abarelix, Antide, and Azaline.
 8. The aqueous injectablesolution of claim 1, wherein said acid is present in at least equimolaramounts with said LHRH antagonist.
 9. The aqueous injectable solution ofclaim 1, which comprises about 500 mg Cetrorelix, about 2.4 g gluconicacid deltalactone, about 2.0 g Tween 80, about 95 g mannitol, in about 2liters of water.
 10. The aqueous injectable solution of claim 1, whichcomprises about 500 mg D-63 153, about 100 mg Tween 80, and about 475 mgmannitol.
 11. The aqueous injectable solution of an LHRH antagonist ofclaim 1, which comprises about 100 mg Teverelix, abolut 100 mg Tween 80,and about 475 mg mannitol.
 12. A method for producing an aqueousinjectable solution of an LHRH antagonist, which comprises either (a)compounding an injectable solution of an LHRH antagonist an organic,pharmaceutically acceptable acid, and optionally a surfactant and anoptional network former in water, or (b) dissolving a LHRH antagonist,and optionally a surfactant, and an optional network former in apharmaceutically acceptable organic acid, homogenizing the resultingsolution, and recovering it in an injectable form.
 13. The method ofclaim 12, wherein said acid is a carboxylic acid.
 14. The method ofclaim 13, wherein said acid is a hydroxycarboxylic acid.
 15. The methodof claim 14, wherein said hydroxycarboxylic acid is gluconic acid.